Hanna Instruments HI7640-58, Instruction Manual

Page: 12 / 16

Maintenance 12
Process Calibration
Prior to performing a process calibration, a reference meter and probe must be used (or another method) to
determine DO value of the process.
Preparation
• Determine the process DO value, using a calibrated reference meter and probe.
• The process controller and the probe should have previously been calibrated with two standards (probe
slope has been determined).
Procedure
1. Press the
m
key then CAL virtual key.
2. Press Process when it is displayed.
3. Use the
ud
keys to adjust the process value in agreement with the predetermined value.
4. Press
CFM
to confirm and save the calibration.
Note : Process calibration evaluates probe offset if input is reading is less than 20%, or probe slope if values are
over 20%.
12. MAINTENANCE
General Maintenance
• Inspect O-ring for nicks or other damage. Replacing the o ring is advised.
• Do not substitute other grease or lubricants as it may cause the O-ring to swell.
• After long-term storage or cleaning, calibrate the probe.
• After use, rinse the probe with tap water and dry it.
• The DO cap must be kept hydrated.
Cleaning the Smart Cap
• Use a mild detergent and a soft-bristled toothbrush to clean.
• Rinse with water after cleaning and dry with a laboratory tissue.
• Hydrate in purified water before use.
Note : Smart Caps need to be replaced every year.
Smart Cap Replacement
• When the cap approaches annual expiration, a warning screen notifies the user of required replacement.
• Press
h
direct key to read days remaining before expiration.
• When one year is reached the message will change to “Cap Expired”. To maintain measurement accuracy
Smart Cap replacement is mandatory.